125 lines
6.9 KiB
Plaintext
125 lines
6.9 KiB
Plaintext
# Helper to allocate a stream on the heap.
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== code
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# instruction effective address register displacement immediate
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# . op subop mod rm32 base index scale r32
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# . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes
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new-stream: # ad: (addr allocation-descriptor), length: int, elemsize: int, out: (addr handle stream _)
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# . prologue
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55/push-ebp
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89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
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# . save registers
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50/push-eax
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52/push-edx
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# var size/edx: int = elemsize*length (clobbering eax)
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# . eax = elemsize
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax
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# . eax *= length
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31/xor 3/mod/direct 2/rm32/edx . . . 2/r32/edx . . # clear edx
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f7 4/subop/multiply 1/mod/*+disp8 5/rm32/ebp . . 0xc/disp8 . # multiply *(ebp+12) into edx:eax
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# . if overflow abort
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81 7/subop/compare 3/mod/direct 2/rm32/edx . . . . . 0/imm32 # compare edx
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75/jump-if-!= $new-stream:abort/disp8
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# . edx = elemsize*length
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89/copy 3/mod/direct 2/rm32/edx . . . 0/r32/eax . . # copy eax to edx
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# var n/eax: int = size + 12 (for read, write and size)
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05/add-to-eax 0xc/imm32
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# allocate(ad, n, out)
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# . . push args
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ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x14/disp8 . # push *(ebp+20)
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50/push-eax
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ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
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# . . call
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e8/call allocate/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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# eax = out->payload
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8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x14/disp8 . # copy *(ebp+20) to eax
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8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax
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# skip payload->allocid
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05/add-to-eax 4/imm32
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# eax->size = size
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89/copy 1/mod/*+disp8 0/rm32/eax . . . 2/r32/edx 8/disp8 . # copy edx to *(eax+8)
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# clear-stream(eax)
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# . . push args
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50/push-eax
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# . . call
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e8/call clear-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
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$new-stream:end:
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# . restore registers
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5a/pop-to-edx
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58/pop-to-eax
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# . epilogue
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89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
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5d/pop-to-ebp
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c3/return
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$new-stream:abort:
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(abort "new-stream: size too large")
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# never gets here
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test-new-stream:
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# . prologue
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55/push-ebp
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89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
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# var ad/ecx: allocation-descriptor containing 16 bytes
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# . var end/ecx: (addr byte)
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89/<- %ecx 4/r32/esp
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# . var start/edx: (addr byte) = end - 32
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81 5/subop/subtract %esp 0x20/imm32
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89/<- %edx 4/r32/esp
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# . ad = {start, end}
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51/push-ecx
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52/push-edx
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89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
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# var start/edx = ad->curr
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8b/copy 0/mod/indirect 1/rm32/ecx . . . 2/r32/edx . . # copy *ecx to edx
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# var h/ebx: (handle stream byte)
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68/push 0/imm32
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68/push 0/imm32
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89/copy 3/mod/direct 3/rm32/ebx . . . 4/r32/esp . . # copy esp to ebx
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# new-stream(ad, 3, 2, h)
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# . . push args
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53/push-ebx
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68/push 2/imm32
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68/push 3/imm32
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51/push-ecx
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# . . call
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e8/call new-stream/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp
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# eax = out->payload
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8b/copy 1/mod/*+disp8 3/rm32/ebx . . . 0/r32/eax 4/disp8 . # copy *(ebx+4) to eax
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# check-ints-equal(eax, edx, msg)
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# . . push args
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68/push "F - test-new-stream: returns current pointer of allocation descriptor"/imm32
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52/push-edx
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50/push-eax
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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# skip payload->allocid
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05/add-to-eax 4/imm32
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# check-ints-equal(eax->size, 6, msg)
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# . . push args
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68/push "F - test-new-stream: sets size correctly"/imm32
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68/push 6/imm32
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ff 6/subop/push 1/mod/*+disp8 0/rm32/eax . . . . . 8/disp8 # push *(eax+8)
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# . . call
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e8/call check-ints-equal/disp32
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# . . discard args
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
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# the rest is delegated to clear-stream() so we won't bother checking it
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# . reclaim locals
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81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x30/imm32 # add to esp
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# . epilogue
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89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
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5d/pop-to-ebp
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c3/return
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# . . vim:nowrap:textwidth=0
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